About

Dr. Hubert Amrein joined the Texas A&M University Naresh K. Vashisht College of Medicine in 2009 as a professor in the Department of Cell Biology and Genetics. He served as associate department head from 2012 to 2018 before being appointed executive associate dean of research in September 2018. Dr. Amrein earned his PhD from the University of Zurich, Switzerland, and completed postdoctoral studies with Dr. Tom Maniatis at Harvard University and Dr. Richard Axel at Columbia University. Prior to his appointment at Texas A&M University, he was on the faculty of Duke University School of Medicine from 1998 to 2009. Dr. Amrein's research focuses on the neural coding of chemosensory perception and neuropeptide signaling using insect model systems, particularly Drosophila. His laboratory investigates how animals detect and discriminate among thousands of different chemical signals that stimulate olfactory and taste organs. The Drosophila chemosensory systems serve as excellent models due to their structural and functional similarity to mammalian systems, yet with less complexity. Current research in his lab centers on understanding the molecular and neural basis of sugar and amino acid perception, as well as identifying pheromone receptors involved in social behaviors such as courtship, mating, egg laying, and aggression. Additionally, his lab explores receptors and signaling molecules involved in auditory perception, recognizing the importance of acoustic signals alongside pheromone cues in social interactions. Dr. Amrein's laboratory employs a wide range of molecular and genetic tools available in the Drosophila model system, including classic genetic analysis, transgenesis, gene knockout studies, and various RNA and DNA analyses. Cellular and anatomical investigations of chemosensory systems and the central nervous system are conducted using immunological methods and in situ hybridization. Functional analyses of genetically modified animals are pursued through behavioral paradigms and electrophysiological assays, providing comprehensive insights into the molecular and neural mechanisms underlying chemosensory perception and neuropeptide signaling.

Research topics

• Biochemistry
• Biology
• Ecology
• Cell biology
• Psychology
• Chemistry
• Neuroscience
• Genetics
• Communication
• Zoology

Selected publications

• Drosophila FMRFa neuropeptide signaling modulates systemic glycogen metabolism and fitness in a diet-dependent manner

  Frontiers in Endocrinology · 2026-05-12

  articleOpen accessSenior author

  Glycogen is the major carbohydrate reserve in animals, mainly in the muscle and liver. It is mobilized via glycogenolysis to liberate glucose, which is used for glycolysis/mitochondrial respiration in the muscle to produce ATP, or released into the blood to maintain sugar homeostasis especially when nutrients are scarce. Although glycogen homeostasis is critical for animal physiology, the mechanisms controlling glycogen storage and utilization remain poorly understood. We recently showed that Drosophila FMRFa neuropeptide signaling is required for glycogen homeostasis in the jump muscle, a major tissue of FMRFa receptor ( FMRFaR ) expression. Here, we report that glycogen accumulation in the flight muscle and fat body also depends on FMRFa signaling, despite the absence of FMRFaR expression in these tissues. In vivo glucose imaging revealed that neither FMRFa nor FMRFaR mutants show deficits in intracellular glucose levels, consistent with a defect in glycogen synthesis or breakdown. Lastly, mutant flies exhibit reduced lifespan when kept on normal or protein-only food, but not on sugar-only food. These findings reveal that Drosophila FMRFa-FMRFaR signaling is a key modulator of systemic glycogen metabolism, thereby influencing survival and fitness in a diet-dependent manner.

  PublisherOA PDFDOI

• Development of a novel simplified Q-system with integrated temporal expression control

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-04-21

  articleOpen accessSenior authorCorresponding

  Abstract Bimodal gene expression systems have played a major role in uncovering the function of genes, cells and organ systems during and after development. Employed initially in model systems such as flies and mice, advances in gene technology have vastly expanded the number of species in which these systems can be deployed. One of their limitations is the challenge of imposing temporal expression control. Here, we report the incorporation of temperature-sensitive intein modules with different temperature profiles into QF2, the transcription factor anchoring the Q-system widely used in Drosophila and introduced recently into several insect species and the zebrafish D. rerio . Intein removal from temperature-sensitive QF2_INT ts activators in Drosophila larvae and adult flies raised under permissive conditions (18°C to 25°C) renders QF2 active and drives strong expression of QUAS reporters. In contrast, raising Drosophila at restrictive temperatures (23°C to 30°C) keeps QF2_INT ts in a non-functional state unable to bind DNA and therefore, keeping QUAS reporters inactive. We further show that reporter expression can be turned on and off both during development and in flies by changing temperature conditions between restrictive to permissive. Finally, QF2_INT ts animals carrying QUAS-Kir2 . 1 encoding the inward rectifying potassium channel raised under restrictive conditions are fully viable, while raised at or moved as adults to permissive temperature results in embryonic lethality or leads to paralysis. Thus, the intein-based Q-system renders the difficult to employ drug-dependent suppressor QS unnecessary, greatly facilitating temporal regulation of gene expression. Having several advantages over the GAL4 system, the Q system has gained broad acceptance in other insect species and the zebrafish D. rerio , and thus QF2_INT ts drivers can be implemented in many other organisms, including disease-transmitting mosquitoes and poikilotherm vertebrate animals much more closely related to humans, to study gene and cell function at any time during or after development.

  PublisherOA PDFDOI

• Glucose-6-phosphatase is required for organelle reorganization, energy metabolism and motility of <i>Drosophila</i> sperm

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-12-02 · 1 citations

  preprintOpen accessSenior authorCorresponding

  SUMMARY Glucose-6-Phosphatase (G6Pase), a key enzyme in gluconeogenesis and glycogenolysis in the mammalian liver and kidney, converts glucose-6-phosphate to glucose for maintaining systemic blood glucose homeostasis during nutrient deprivation. However, its function has remained elusive in insects, which have no need for G6Pase in sugar homeostasis since they convert glucose-6-phosphate to trehalose, their main circulating sugar, via trehalose phosphate synthase (TPS1). In this study we identify an unexpected and essential requirement for G6Pase in Drosophila male fertility, specifically to produce motile sperm. In G6P mutant males, spermatogenesis and spermiogenesis appear to proceed normally, leading to the production and transfer of mature sperm. However, once inside the female reproductive tract, G6P mutant sperm exhibit severely reduced tail beat frequency and only rarely enter an egg. Moreover, when compared to wild type sperm, G6P -deficient sperm are depleted more rapidly from the spermatheca and seminal receptacle, the female sperm storage organs. Immunohistochemical analyses show that G6P mutant spermatocytes present with an enlarged and stressed endoplasmic reticulum (ER) and a diminished Golgi apparatus. Additionally, the acrosome, a Golgi derived organelle that is critical for sperm capacitation, exhibits diminished expression of the transmembrane protein SNEAKY, which is essential to breakdown the sperm plasma membrane after fertilization. Metabolic analyses show impairment of both basal and compensatory glycolysis, as well as ATP production, in testes of G6P mutant males. Taken together, our investigations unveil a novel and crucial function for G6Pase in male fertility, highlighting its importance in regulating energy homeostasis in reproductive tissues.

  PublisherOA PDFDOI

• <i>Drosophila</i> neuronal Glucose-6-Phosphatase is a modulator of neuropeptide release that regulates muscle glycogen stores via FMRFamide signaling

  Proceedings of the National Academy of Sciences · 2024-07-15 · 3 citations

  articleOpen accessSenior authorCorresponding

  Neuropeptides (NPs) and their cognate receptors are critical effectors of diverse physiological processes and behaviors. We recently reported of a noncanonical function of the Drosophila Glucose-6-Phosphatase ( G6P ) gene in a subset of neurosecretory cells in the central nervous system that governs systemic glucose homeostasis in food-deprived flies. Here, we show that G6P- expressing neurons define six groups of NP-secreting cells, four in the brain and two in the thoracic ganglion. Using the glucose homeostasis phenotype as a screening tool, we find that neurons located in the thoracic ganglion expressing FMRFamide NPs ( FMRFa G6P neurons) are necessary and sufficient to maintain systemic glucose homeostasis in starved flies. We further show that G6P is essential in FMRFa G6P neurons for attaining a prominent Golgi apparatus and secreting NPs efficiently. Finally, we establish that G6P- dependent FMRFa signaling is essential for the build-up of glycogen stores in the jump muscle which expresses the receptor for FMRFamides. We propose a general model in which the main role of G6P is to counteract glycolysis in peptidergic neurons for the purpose of optimizing the intracellular environment best suited for the expansion of the Golgi apparatus, boosting release of NPs and enhancing signaling to respective target tissues expressing cognate receptors.

  PublisherOA PDFDOI

• Reviewer #1 (Public Review): Opposing chemosensory functions of closely related gustatory receptors

  2023-11-17

  peer-reviewOpen accessSenior author

  Most animals have functionally distinct populations of taste cells, expressing receptors that are tuned to compounds of different valence. This organizational feature allows for discrimination between chemicals associated with specific taste modalities and facilitates differentiating between unadulterated foods and foods contaminated with toxic substances. In the fruit fly D. melanogaster, primary sensory neurons express taste receptors that are tuned to distinct groups of chemicals, thereby activating neural ensembles that elicit either feeding or avoidance behavior. Members of a family of ligand gated receptor channels, the Gustatory receptors (Grs), play a central role in these behaviors. In general, closely related, evolutionarily conserved Gr proteins are co-expressed in the same type of taste neurons, tuned to chemically related compounds, and therefore triggering the same behavioral response. Here, we report that members of the Gr28 subfamily are expressed in largely non-overlapping sets of taste neurons in Drosophila larvae, detect chemicals of different valence and trigger opposing feeding behaviors. We determined the intrinsic properties of Gr28 neurons by expressing the mammalian Vanilloid Receptor (VR1), which is activated by capsaicin, a chemical to which wildtype Drosophila larvae do not respond. When VR1 is expressed in Gr28a neurons, larvae become attracted to capsaicin, consistent with reports showing that Gr28a itself encodes a receptor for nutritious RNA. In contrast, expression of VR1 in two pairs of Gr28b.c neurons triggers avoidance to capsaicin. Moreover, neuronal inactivation experiments show that the Gr28b.c neurons are necessary for avoidance of several bitter compounds. Lastly, behavioral experiments of Gr28 deficient larvae and live Ca2+ imaging studies of Gr28b.c neurons revealed that denatonium benzoate, a synthetic bitter compound that shares structural similarities with natural bitter chemicals, is a ligand for a receptor complex containing a Gr28b.c or Gr28b.a subunit. Thus, the Gr28 proteins, which have been evolutionarily conserved over 260 million years in insects, represent the first taste receptor subfamily in which specific members mediate behavior with opposite valence.

  PublisherDOI

• Author Response: Opposing chemosensory functions of closely related gustatory receptors

  2023-11-17

  peer-reviewOpen accessSenior author

  Most animals have functionally distinct populations of taste cells, expressing receptors that are tuned to compounds of different valence. This organizational feature allows for discrimination between chemicals associated with specific taste modalities and facilitates differentiating between unadulterated foods and foods contaminated with toxic substances. In the fruit fly D. melanogaster, primary sensory neurons express taste receptors that are tuned to distinct groups of chemicals, thereby activating neural ensembles that elicit either feeding or avoidance behavior. Members of a family of ligand gated receptor channels, the Gustatory receptors (Grs), play a central role in these behaviors. In general, closely related, evolutionarily conserved Gr proteins are co-expressed in the same type of taste neurons, tuned to chemically related compounds, and therefore triggering the same behavioral response. Here, we report that members of the Gr28 subfamily are expressed in largely non-overlapping sets of taste neurons in Drosophila larvae, detect chemicals of different valence and trigger opposing feeding behaviors. We determined the intrinsic properties of Gr28 neurons by expressing the mammalian Vanilloid Receptor (VR1), which is activated by capsaicin, a chemical to which wildtype Drosophila larvae do not respond. When VR1 is expressed in Gr28a neurons, larvae become attracted to capsaicin, consistent with reports showing that Gr28a itself encodes a receptor for nutritious RNA. In contrast, expression of VR1 in two pairs of Gr28b.c neurons triggers avoidance to capsaicin. Moreover, neuronal inactivation experiments show that the Gr28b.c neurons are necessary for avoidance of several bitter compounds. Lastly, behavioral experiments of Gr28 deficient larvae and live Ca2+ imaging studies of Gr28b.c neurons revealed that denatonium benzoate, a synthetic bitter compound that shares structural similarities with natural bitter chemicals, is a ligand for a receptor complex containing a Gr28b.c or Gr28b.a subunit. Thus, the Gr28 proteins, which have been evolutionarily conserved over 260 million years in insects, represent the first taste receptor subfamily in which specific members mediate behavior with opposite valence.

  PublisherDOI

• Opposing chemosensory functions of closely related gustatory receptors

  eLife · 2023 · 13 citations

  Senior authorCorresponding
  • Neuroscience
  • Biology
  • Cell biology

  proteins, which have been evolutionarily conserved over 260 million years in insects, represent the first taste receptor subfamily in which specific members mediate behavior with opposite valence.

  PublisherDOI

• Reviewer #2 (Public Review): Opposing chemosensory functions of closely related gustatory receptors

  2023-11-17

  peer-reviewOpen accessSenior author

  Most animals have functionally distinct populations of taste cells, expressing receptors that are tuned to compounds of different valence. This organizational feature allows for discrimination between chemicals associated with specific taste modalities and facilitates differentiating between unadulterated foods and foods contaminated with toxic substances. In the fruit fly D. melanogaster, primary sensory neurons express taste receptors that are tuned to distinct groups of chemicals, thereby activating neural ensembles that elicit either feeding or avoidance behavior. Members of a family of ligand gated receptor channels, the Gustatory receptors (Grs), play a central role in these behaviors. In general, closely related, evolutionarily conserved Gr proteins are co-expressed in the same type of taste neurons, tuned to chemically related compounds, and therefore triggering the same behavioral response. Here, we report that members of the Gr28 subfamily are expressed in largely non-overlapping sets of taste neurons in Drosophila larvae, detect chemicals of different valence and trigger opposing feeding behaviors. We determined the intrinsic properties of Gr28 neurons by expressing the mammalian Vanilloid Receptor (VR1), which is activated by capsaicin, a chemical to which wildtype Drosophila larvae do not respond. When VR1 is expressed in Gr28a neurons, larvae become attracted to capsaicin, consistent with reports showing that Gr28a itself encodes a receptor for nutritious RNA. In contrast, expression of VR1 in two pairs of Gr28b.c neurons triggers avoidance to capsaicin. Moreover, neuronal inactivation experiments show that the Gr28b.c neurons are necessary for avoidance of several bitter compounds. Lastly, behavioral experiments of Gr28 deficient larvae and live Ca2+ imaging studies of Gr28b.c neurons revealed that denatonium benzoate, a synthetic bitter compound that shares structural similarities with natural bitter chemicals, is a ligand for a receptor complex containing a Gr28b.c or Gr28b.a subunit. Thus, the Gr28 proteins, which have been evolutionarily conserved over 260 million years in insects, represent the first taste receptor subfamily in which specific members mediate behavior with opposite valence.

  PublisherDOI

• RNA Taste Is Conserved in Dipteran Insects

  Journal of Nutrition · 2023 · 12 citations

  Senior authorCorresponding
  • Biology
  • Zoology
  • Genetics

  BACKGROUND: Ribonucleosides and RNA are an underappreciated nutrient group essential during Drosophila larval development and growth. Detection of these nutrients requires at least one of the 6 closely related taste receptors encoded by the Gr28 genes, one of the most conserved insect taste receptor subfamilies. OBJECTIVES: We investigated whether blow fly larvae and mosquito larvae, which shared the last ancestor with Drosophila about 65 and 260 million years ago, respectively, can taste RNA and ribose. We also tested whether the Gr28 homologous genes of the mosquitoes Aedes aegypti and Anopheles gambiae can sense these nutrients when expressed in transgenic Drosophila larvae. METHODS: Taste preference in blow flies was examined by adapting a 2-choice preference assay that has been well-established for Drosophila larvae. For the mosquito Aedes aegypti, we developed a new 2-choice preference assay that accommodates the aquatic environment of these insect larvae. Finally, we identified Gr28 homologs in these species and expressed them in Drosophila melanogaster to determine their potential function as RNA receptors. RESULTS: Larvae of the blow fly Cochliomyia macellaria and Lucilia cuprina are strongly attracted to RNA (0.5 mg/mL) in the 2-choice feeding assays (P < 0.05). Similarly, the mosquito Aedes aegypti larvae showed a strong preference for RNA (2.5 mg/mL) in an aquatic 2-choice feeding assay. Moreover, when Gr28 homologs of Aedes or Anopheles mosquitoes are expressed in appetitive taste neurons of Drosophila melanogaster larvae lacking their Gr28 genes, preference for RNA (0.5 mg/mL) and ribose (0.1 M) is rescued (P < 0.05). CONCLUSIONS: The appetitive taste for RNA and ribonucleosides in insects emerged about 260 million years ago, the time mosquitoes and fruit flies diverged from their last common ancestor. Like sugar receptors, receptors for RNA have been highly conserved during insect evolution, suggesting that RNA is a critical nutrient for fast-growing insect larvae.

  PublisherDOI

• Opposing chemosensory functions of closely related gustatory receptors

  2023-08-10 · 2 citations

  preprintOpen accessSenior author

  Abstract Most animals possess functionally distinct population of taste cells, expressing receptors that are tuned to compounds of different valence. This organizational feature allows for discrimination between chemicals associated with different taste modalities and facilitates sensing of foods contaminated with toxic chemicals. In the fruit fly D. melanogaster, primary sensory neurons express taste receptors that are tuned to distinct chemicals, thereby activating neural ensembles that elicit either feeding or avoidance behavior. Members of a family of ligand gated receptor channels, the Gustatory receptors (Gr), play a central role in these behaviors. In general, closely related, evolutionarily conserved Gr proteins are co-expressed in the same type of taste neurons, tuned to chemically related compounds and therefore triggering the same behavioral response. Here, we report that members of the Gr28 subfamily are expressed in largely non-overlapping sets of taste neurons in Drosophila larvae, detect chemicals of different valence and trigger opposing feeding behaviors. We determined the intrinsic properties of Gr28 neurons by expressing the mammalian Vanilloid Receptor (VR1), which is activated by capsaicin, a chemical to which wild type Drosophila larvae do not respond. When VR1 is expressed in Gr28a neurons, larvae become attracted to capsaicin, whereas expression of VR1 in Gr28bc neurons triggers avoidance to capsaicin. Thus, the Gr28 proteins, which have been evolutionarily conserved over the last 65 million years in insects, represent the first taste receptor subfamily in which specific members mediate behavior with opposite valence. We also identified denatonium benzoate, a synthetic bitter compound that shares structural similarities with natural bitter chemicals, as a ligand for a receptor complex containing a Gr28bc or Gr28ba receptor subunit. Alphafold structure prediction, combined with the limited sequence conservation in the putative binding pockets of various Gr28 proteins, creates a theoretical framework for targeted in vivo structure function studies to precisely map residues critical for ligand recognition.

  PublisherDOI

Recent grants

• NIH Grant R01DC013967

  NIH · $1.2M · 2019

• NIH Grant R01DC009014

  NIH · $1.6M · 2014

• NIH Grant R21DC015327

  NIH · $408k · 2019

• Convergence of Cellular and Molecular Pathways in Appetitive Taste

  NIH · $4.5M · 2002–2021

• NIH Grant R01GM060234

  NIH · $1.1M · 2004

Frequent coauthors

• Shinsuke Fujii

  Kyushu University

  30 shared

• Natasha Thorne

  25 shared

• Steven M. Bray

  20 shared

• Tetsuya Miyamoto

  Bryan College

  19 shared

• Yan Chen

  16 shared

• Christopher Jagge

  Bryan College

  10 shared

• Ji‐Eun Ahn

  Texas A&M University

  10 shared

• Akemi Toyama

  Duke University Hospital

  9 shared

Labs

• Hubert Amrein LabPI

Education

• Ph.D., Nutrition

  Texas A&M University

  2000

• M.S., Nutrition

  Texas A&M University

  1996

• B.S., Nutrition

  Texas A&M University

  1994